1. Field of the Invention
The present invention relates to a method for upgrading heavy fuel oil and producing gas turbine fuel, and also relates to a method and system for generating electric power by a gas turbine.
2. Description of the Related Art
Heavy fuel oil has hitherto been mainly used in equipment aiming at generation of electric power and supply of heat by a boiler. Meanwhile, studies have recently been made with intent to use heavy fuel oil as gas turbine fuel. When heavy fuel oil is used as gas turbine fuel, it is required to reduce contaminant/impurity of heavy metals contained in the heavy fuel oil, particularly vanadiums. The reason is that vanadium causes corrosion of a gas turbine under high temperatures. One method of reducing the vanadium contaminant/impurity comprises the steps of mixing heavy fuel oil with water, and decomposing the heavy fuel oil under a reaction condition where water is brought into a supercritical or sub-supercritical state, for separation into a light oil component and a residual component, the light oil component being used as the gas turbine fuel (see, e.g., Patent Reference 1: JP-A-11-80750 (Abstract)). According to another method, an asphaltene component in the heavy fuel oil is separated and removed by using an asphaltene-insoluble solvent, such as pentane or isobutane, whereby vanadium contained in the asphaltene component is removed and other components are used as the gas turbine fuel (see, e.g., Patent Document 2: Domestic Re-Publication of PCT Publication WO2002/044307 (page 9, 10-20 lines).